Generally with much reduced functionality compared to a full app. Can't mobile deposit from the web, and couldn't use a one-time access method to use my bank's ATM without my card (which did only occur once, but it was damn convenient).

Also, one of my banking institutions is a small credit union whose website does not work well on mobile, but has a well functioning android and iOS app.

For my bank I can only use their android/ios 2-factor app or their own physical authenticator, which I also have, but I found out the hard way that it's vulnerable to rain when in a pocket of a backpack. It is impossible to do anything without the 2nd factor auth of course.

Here basically every bank now requires an app for 2 factor. Even the government is going there.